The present invention relates to a wheel suspension for the driven rear wheels of motor vehicles, with a wheel carrier supporting the wheel, which is connected by way of cross guide member arranged at a vertical distance from one another with the vehicle body or an auxiliary frame to be fastened thereon, whereby one of the cross guide members is constructed torsion-resistant and is operatively connected on the side of the wheel with the wheel carrier by way of two bearings disposed one behind the other, of which one bearing is more elastic in the plane of the cross guide member than the other.
A wheel suspension of this type (DE-A No. 25 43 189) includes a lower cross guide member which is constructed torsion-resistant about a vehicle transverse axis, as well as an upper simple rod-shaped cross guide member. Moments exerted about a transverse axis by the wheel carrier on the wheel suspension as a result of braking or starting forces are absorbed alone by the lower cross guide member because the upper rod guide member is unable to contribute anything for that purpose. The lower cross guide member is connected with the wheel carrier by way of two bearings disposed one behind the other in plan view, of which the forward bearing is to be radially more soft than the rear bearing. In this manner, the wheel is to experience a toe-in increase under the influence of lateral forces within the scope of the elasticity of the bearing on the wheel carrier side of the lower cross guide member. The pivot axis which is defined by the two bearings of the lower cross guide member on the wheel carrier side, between this cross guide member and the wheel carrier and the pivot axis of the cross guide member on the side of the body intersect in plan view in a point which is located in front of the wheel axis, and this means that also the starting and brake pitching pole is located in front of the axle which is desirable as such. A disadvantage of this axle, however, resides in the fact that the inward spring-deflecting wheel is displaced very markedly in the direction of toe-out which entails a strong oversteering driving behavior in curves.
Another known axle of about this type of construction (Automobiltechnische Zeitschrift 79 "1977" 6, Page 220) therefore provides the point of intersection of the pivot axis of the lower cross guide member on the side of the wheel carrier with the pivot axis of this cross guide member on the body side far to the rear of the wheel axis, as viewed in plan view. The adjustment of the wheel during inward and outward spring deflection in the direction of toe-out is avoided thereby. However, this again leads to the fact that with such a type of wheel suspension, on the one hand, a good starting pitching compensation is possible but, on the other hand, only a relatively small braking pitching compensation is feasible.
The present invention is concerned with the task to provide a wheel suspension of the aforementioned type of construction which enables not only a good acceleration (starting) pitching compensation but also a good deceleration (braking) pitching compensation and additionally makes possible an intentional influencing of the toe-in progress during the inward and outward spring deflection.
The underlying problems are solved in a wheel suspenion of the aforementioned type in that two support guide members disposed one behind the other and extending approximately transversely are provided at a vertical distance from the torsion and bending-resistant cross guide member. The point of intersection of the pivot axis on the side of the wheel carrier and of the pivot axis on the side of the body of the torsion-resistant cross guide member which is located in front of the wheel axis, makes it possible to so select the pole of the wheel suspension that an obliquely forwardly upwardly rising line of action is provided for the brake force as also for the driving force so that not only a good acceleration (starting) pitching compensation, but also a good deceleration (braking) pitching compensation are attainable. Therebeyond, such a strong steering movement about a vertical axis can be imposed upon the wheel carrier during the inward and outward spring deflection movement owing to the support guide members which are arranged at a vertical distance from the torsion-resistant cross guide members and are disposed one behind the other as well as extend transversely, that in the course of the spring movement, no wheel position change in the direction of toe-out but under some circumstances even in the direction of toe-in takes place. The vehicle thus receives a neutral, possibly even understeering driving behavior in the curve.
As the moments exerted by the wheel carrier on the wheel suspension during the starting and during the braking are absorbed exclusively by the bending and torsion-resistant cross guide member, it is more simple to design and match the wheel suspension with regard to the elastokinematics. The wheel suspension furthermore has a small space requirement in the vehicle longitudinal direction. Furthermore, a complete preassembly of the axle at an auxiliary frame or at an elastically suspended driving bogie or the like is possible. Finally, the novel axle also permits additionally an "active" steering of the wheels of this axle, in that one of two upper support guide members is adjusted essentially in the longitudinal direction thereof.